When production from a hydrocarbon well attainable through natural means (e.g., pressure within the wellbore) is no longer sufficient for the well to remain economically viable, numerous types of secondary recovery methods exist to increase the productivity of the well. One such method includes use of a downhole pump that is inserted into the wellbore, then actuated to draw hydrocarbons and/or other fluids toward the surface. Conventionally, downhole pumps are actuated by physically manipulating values and/or other operable parts from the surface, through movement of a pump jack or similar powered device connected to the downhole pump using a long string of joined connectors, termed “sucker rods.”
When in use, these sucker rods are used in conjunction with sucker rod guides to prevent contact between sucker rods and production tubing. Depending on how straight or how vertical the individual wellbore is, these guides may be spaced on the rod depending on the engineering recommendations. Commonly, these rod guides are made using composite materials and thermoplastics including, e.g., polyphthalamide nylon, polyphenylene sulfide, and polyethylene.
The standard method of fitting a rod guide to a sucker rod involves direct-injection molding of the guide onto the rod body. This works reasonably well for instances where the sucker rod is steel, due to surface irregularities allowing the guide to hold in place. However, when the sucker rod is made of fiberglass, the smooth surface may allow the guide to slip when the sucker rod is under load. As a result, fiberglass sucker rods require an additional procedure in which the rod is sanded down at each guide location and a bead of epoxy is applied to the rod and allowed to harden into a “key” prior to the molding process to prevent slippage.
However, this process has drawbacks. Since the retention of the guide in place is directly related to the manual application of the epoxy, inconsistency in application can lead to wide variability in retention loading. In addition, the high heat (600° F.) of the direct-injection molding process may stress the fiberglass and cause damage. Finally, even a slight misalignment of the rod with the mold can subject the rod to clamping forces which damage it and require extensive inspection.
A need exists for a rod guide which can be used with both steel and fiberglass rods with reliability and consistency between applications.
Embodiments of the apparatus described herein meet this and other needs.
One or more embodiments are described below with reference to the listed Figures.